Creatine ester pronutrient compounds and formulations

ABSTRACT

The present invention describes a method for providing creatine to an animal, which includes receiving a creatine ester by the animal. The creatine ester is suitable for being modified by the animal to form creatine.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 120 to PatentCooperation Treaty (PCT) Application PCT/US01/28788 filed in the UnitedStates of America on Sep. 14, 2001. The Patent Cooperation TreatyApplication PCT/US01/28788 claimed priority under 35 U.S.C. § 119(e) toU.S. Provisional Application No. 60/232,969 filed Sep. 14, 2000. ThePatent Cooperation Treaty Application PCT/US01/28788 and the U.S.Provisional Application No. 60/232,969 are herein incorporated byreference in their entirety.

FIELD OF THE INVENTION

The present invention generally relates to the field of creatine, andparticularly to creatine ester pronutrient compounds and formulations.

BACKGROUND OF THE INVENTION

Creatine is an endogenous nutrient produced naturally by the liver inmost vertebrates. The uses of creatine are many, including use as asupplement to increase muscle mass and enhance muscle performance aswell as in emerging applications in the treatment of neuromusculardisorders.

Typically, creatine is taken up into muscle cells by specific receptorsand converted to phosphocreatine by creatine kinase. Muscle cells,including skeletal muscle and the heart muscle, function by utilizingcellular energy released from the conversion of adenosine triphosphate(ATP) to adenosine diphosphate (ADP). The amount of phosphocreatine inthe muscle cell determines the amount of time it will take for themuscle to recover from activity and regenerate adenosine triphosphate(ATP). Phosphocreatine is a rapidly accessible source of phosphaterequired for regeneration of adenosine triphosphate (ATP) and sustaineduse of the muscle.

For example, energy used to expand and contract muscles is supplied fromadenosine triphosphate (ATP). Adenosine triphosphate (ATP) ismetabolized in the muscle by cleaving a phosphate radical to releaseenergy needed to contract the muscle. Adenosine diphosphate (ADP) isformed as a byproduct of this metabolism. The most common sources ofadenosine triphosphate (ATP) are from glycogen and creatine phosphate.Creatine phosphate is favored as a ready source of phosphate because itis able to resynthesize adenosine triphosphate (ATP) at a greater ratethan is typically achieved utilizing glycogen. Therefore, increasing theamount of creatine in the muscle increases the muscle stores ofphosphocreatine and has been proven to increase muscle performance andincrease muscle mass.

However, creatine itself is poorly soluble in an aqueous solution.Further, creatine is not well absorbed from the gastrointestinal (GI)tract, which has been estimated to have a 1 to 14 percent absorptionrate. Thus, current products require large amounts of creatine to beadministered to be effective, typically 5 grams or more. Additionally,side effects such as bloating, gastrointestinal (GI) distress, diarrhea,and the like are encountered with these high dosages.

Therefore, it would be desirable to provide an improved approach forenhancing absorption of creatine.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to creatine esterpronutrients and formulations. In a first aspect of the presentinvention, a method for providing creatine to an animal includesreceiving a creatine ester by the animal. The creatine ester is suitablefor being modified by the animal to form creatine.

In a second aspect of the present invention, a food supplement includesa creatine ester suitable for being modified by an animal to formcreatine. In a third aspect of the present invention, a method forproviding creatine to an animal includes receiving an ester derivativeof creatine by the animal. The ester derivative of creatine is suitablefor acting as a pronutrient in an animal.

In a fourth aspect of the present invention, a composition of matterincludes:

wherein R represents an ester.

In a fifth aspect of the present invention, a method of producing acreatine pronutrient includes reacting a hydrated form of creatine withan alcohol in an acidic environment wherein a product is formedincluding a creatine ester pronutrient.

It is to be understood that both the forgoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention as claimed. The accompanyingdrawings, which are incorporated in and constitute a part of thespecification, illustrate an embodiment of the invention and togetherwith the general description, serve to explain the principles of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The numerous advantages of the present invention may be betterunderstood by those skilled in the art by reference to the accompanyingfigures in which:

FIG. 1A is an illustration depicting conversion of creatine tocreatinine;

FIG. 1B is a depiction of an exemplary embodiment of the presentinvention wherein the processing of creatine monohydrate versus acreatine ester by the body is shown;

FIG. 1C is a flow diagram illustrating an exemplary embodiment of thepresent invention wherein a pronutrient derivative of creatine iscreated through the modification of an acid moiety by ester bondattachment;

FIG. 1D is an illustration of an embodiment of the present invention inwhich a graph depicting solubility and partition coefficients ofcreatine ethyl ester versus creatine monohydrate are shown;

FIGS. 2A, 2B, 2C, 2D, 2E, 2F, 2G, 2H, 2I, 2J, 2K, 2L, 2M and 2N areillustrations of exemplary compounds of the present invention;

FIG. 3 is an illustration depicting an exemplary embodiment of thepresent invention wherein a creatine ethyl ester compound is produced bysolvating creatine monohydrate in dry ethyl alcohol in an acidicatmosphere;

FIG. 4 is an illustration of an embodiment of the present inventionwherein additional methods and processes are shown for the production ofa creatine ester; and

FIG. 5 is an illustration depicting an exemplary embodiment of thepresent invention wherein a creatine benzyl ester compound is producedby solvating anhydrous creatine in dry benzyl alcohol in an acidicatmosphere.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the presently preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings.

Referring generally now to FIGS. 1 through 5, exemplary embodiments ofthe present invention are shown. Creatine,N-aminoiminomethyl-N-methylglycine, is an endogenous nutrient which maybe produced in the liver and kidneys. Typically, creatine is produced bythe transfer of the guanidine moiety of arginine to glycine, which isthen methylated to give creatine. Creatine may be represented by thefollowing formula:

Creatine phosphate is formed in the body and may be represented by thefollowing formula:

Creatine is converted to creatine phosphate by the creatine kinaseenzyme. The creatine phosphate transfers its phosphate to adenosinediphosphate (ADP) to accomplish the regeneration of adenosinetriphosphate (ATP). Adenosine triphosphate (ATP) may then be utilized bythe muscles as a source of energy. Thus, by providing a formulation andmethod for enhanced absorption of creatine, the muscle levels ofphosphocreatine will be elevated. As a result of this, muscle mass andperformance may be increased, thereby permitting a variety oftherapeutic applications.

Studies in the laboratory have shown that the aqueous solubility andpartition coefficient of creatine monohydrate are 15.6±2.1 mg/mL and0.015±0.007, respectively. The low oral bioavailability of creatine mayderive not only from its low lipophilicity and concomitant poor membranepermeability, but also from rapid conversion to creatinine in the acidiccondition of the stomach, and shown in FIG. 1A.

At a gastric pH range of 1-2, the equilibrium between creatine andcreatinine shifts to the right such that the creatinine/creatine ratiomay be greater than or equal to 30. See Edgar, G.; Shiver, H. E., TheEquilibrium Between Creatine and Creatinine in Aqueous Solution. TheEffect of Hydrogen Ion. J. Amer. Chem. Soc. 1925, 47, 1179-1188, whichis herein incorporated by reference in its entirety.

Referring now to FIG. 1B, an embodiment of the present invention isshown wherein creatine ester metabolism is shown. By providing acreatine ester, a more water-soluble compound will be provided than therelatively insoluble zwitterionic creatine, and increasedlipophilicities will allow for better membrane permeability.

For example, by masking the carboxylic acid functional group ofcreatinine by esterification, the formation of creatinine in the stomachwill be precluded, resulting in an efficient delivery of the creatineesters to the intestine where absorption may occur. Standard supplementscontaining creatine monohydrate undergo substantial conversion tocreatinine in the stomach. This, coupled with the low absorption ofcreatine in the intestine, leads to reduced amounts of creatine reachingthe muscle cell.

In contrast, creatine esters do not undergo conversion to creatinine inthe stomach and are more readily absorbed in the intestine. As a result,blood creatine concentrations are higher and thus more creatine isavailable to the muscle. As a result of this, the intestinal absorptionof creatine ester will be significantly greater than that observed withcreatine monohydrate. An additional advantage of creatine esters isthat, as the creatine ester compound moves from the intestinal tissueinto the bloodstream, the creatine ester compounds themselves arebiologically inactive, but esterase enzymes present in both theintestinal cells and the blood break the ester bonds of creatine ester,converting it to biologically active creatine. In other words, theadvantages of the creatine ester are preserved during transport, such asincreased solubility and permeability, but when needed, the creatine isavailable to be converted into its biologically active form.

Compared to creatine monohydrate, the increased blood levels of creatineobtained with supplements containing the creatine ester compounds areexpected to result in increased responses at the target tissue (i.e.muscle). Thus the increased stability and improved absorption ofcreatine ester results in much greater blood creatine levels than can beachieved with creatine monohydrate supplements. Once in the blood,creatine is transported into the muscle cells, where it is converted tocreatine phosphate that will then be consumed by the cell during muscleperformance.

Following is a brief overview of the various disease states that may beresponsive to creatine supplementation. It should be noted that theproposed disease states below involve increasing creatine in a diversearray of cells including not only muscle but neurons and endothelialcells as well.

Parkinson's Disease

Parkinson's disease depletes dopamine levels in the brain. Energyimpairment may play a role in the loss of dopaminergic neurons. Studiesinvolving rats showed that a diet supplemented with creatine for 2 weeksresulted in only a 10% reduction in brain dopamine as compared to a 70%dopamine depletion in nonsupplemented rodents. See Matthews R T,Ferrante R J, Klivenyi P, Yang L, Klein A M, Mueller G, Kaddurah-Daouk Rand Beal M F. Creatine and cyclocreatine attenuate MPTP neurotoxicity.Exp Neurol 157: 142-149, (1999), which is herein incorporated byreference in its entirety. These pre-clinical studies suggest thatcreatine dietary supplements may have a positive therapeutic outcome inslowing the onset and decreasing the severity of the disease.

Huntington's Disease

Alterations in energy production may also contribute to the developmentof brain lesions in patients with Huntington's disease. Rats fed a dietsupplemented with creatine for 2 weeks responded better when exposed to3-nitropropionic acid which mimics the changes in energy metabolism seenwith Huntington's disease. The creatine fed animals had 83% less lesionvolume than nonsupplemented animals (Matthews et al., 1999).

Mitochondrial Pathologies

Creatine supplementation increased the life-span of GP3A transgenic mice(a model for amyotrophic lateral sclerosis) up to 26 days. A studyinvolving patients with a variety of neuromuscular disorders alsobenefited from creatine supplementation. See Klivenyi P, Ferrante R J,Matthews R T, Bogdanov M B, Klein A M, Andreassen O A, Mueller G, WermerM, Kaddurah-Daouk R and Beal M F. Neuroprotective effects of creatine ina transgenic animal model of amyotrophic lateral sclerosis. Nat Med 5:347-350, (1999), which is herein incorporated by reference in itsentirety. Increases in high-density strength measurements were seen inthese patients following a short-term trail of creatine (10 g/d for 5days with 5g/d for 5 to 7 days). Creatine supplementation also resultedin increased body weight in these patients.

Stroke

Creatine may also be useful in patients with hypoxia and ishemic braindiseases such as stroke. Creatine has been shown to reduce damage to thebrainstem and hippocampus resulting from hypoxia. See Balestrino M,Rebaudo R and Lunardi G. Exogenous creatine delays anoxic depolarizationand protects from hypoxic damage. Dose-effect relationship. Brain Res816:124-130, (1999); and Dechent P, Pouwels P J, Wilken B, Hanefeld Fand Frahm J. Increase of total creatine in human brain after oralsupplementation of creatine-monohydrate. Am J Physiol 277: R698-R704,(1999) which are herein incorporated by reference in their entirety.This neuroprotection may be due to prevention of ATP depletion. Studiessuggest that supplementation of humans with creatine does increase brainlevels of creatine. See Wick M, Fujimori H, Michaelis T and Frahm J.Brain water diffusion in normal and creatine-supplemented rats duringtransient global ischemia. Magn Reson Med 42: 798-802, (1999); MichaelisT, Wick M, Fujimori H, Matsumura A and Frahm J. Proton MRS of oralcreatine supplementation in rats. Cerebral metabolite concentrations andischemic challenge. NMR Biomed 12: 309-314, (1999); and Malcon C,Kaddurah-Daouk R and Beal M. Neuroprotective effects of creatineadministration against NMDA and malonate toxicity. Brain Res 860:195-198, (2000) which are herein incorporated by reference in theirentirety. High brain creatine levels may offer protection to ischemicbrain injury.

Muscular Diseases

Patients with various muscular dystrophies supplemented with creatinefor 8 weeks showed a 3% increase in strength and a 10% improvement inneuromuscular symptom score. Short-term creatine supplementation alsoimproved strength in patients with rheumatoid arthritis, but did notchange physical function. See Felber S, Skladal D, Wyss M, Kremser C,Koller A and Sperl W. Oral creatine supplementation in Duchenne musculardystrophy: A clinical and 31P magnetic resonance spectroscopy study.Neurol Res 22: 145-150 (2000), which is herein incorporated by referencein its entirey. Patients with McArdles disease showed improvements whengiven creatine. The improvements included reduced frequency of musclepain and increased exercise performance and strength. Increases inexercise performance were also seen during ischemic episodes. See WillerB, Stucki G, Hoppeler H, Bruhlmann P and Krahenbuhl S. Effects ofcreatine supplementation on muscle weakness in patients with rheumatoidarthritis. Rheumatology 39: 293-298, (2000), which is hereinincorporated by reference in its entirety.

Heart Disease

Given the role of creatine phosphate as an immediate and readilyaccessible source of phosphate for regeneration of ATP, it follows thatcreatine supplementation may have a favorable impact diseases of theheart. In patients with congestive heart failure creatinesupplementation produced an increase in exercise performance as measuredby strength and endurance. See Gordon A, Hultman E, Kaijser L,Kristjansson S, Rolf C J, Nyquist O and Sylven C. Creatinesupplementation in chronic heart failure increases skeletal musclecreatine phosphat and muscle performanmce. Cardiovasc Res 30: 413-418,(1995), which is herein incorporated by reference in its entirety. Anadditional consideration with ramifications in the management ofcardiovascular diseases is the report that creatine supplementation canlower cholesterol and triglyceride levels in humans. See Earnest C P,Almada A L and Mitchell T L. High-performance capillaryelectrophoresis-pure creatine monohydrate reduces blood lipids in menand women. Clin Sci (Colch) 91: 113-118, (1996), which is hereinincorporated by reference in its entirety.

Muscle Fatigue Secondary to Aging

Research on adults over 60-years of age suggest that creatinesupplementation may delay muscle fatigue, but does not affect bodycomposition or strength (Rawson and Clarkson, 2000). See Rawson E S andClarkson P M. Acute creatine supplementation in older men. Int J SportsMed 21: 71-75, (2000), which is herein incorporated by reference in itsentirety. As with many of the therapeutic implication studies, thesepreliminary experiments were performed over a short (i.e. less than30-day) period of time, where the effects of creatine supplementation onmuscle mass and strength may not be fully demonstrated. While theeffects observed in the elderly were not profound, these initial reportssuggest the health benefits to this growing population are promising.

Referring now to FIG. 1C, an exemplary embodiment of the presentinvention is shown wherein a pronutrient derivative of creatine iscreated through the modification of an acid moiety by ester bondattachment. Creatine 102 is changed by modifying an acid moiety throughester bond attachment 104. For example, creatine may be converted tocreatine ethyl ester 106, which has a formula as follows:

A creatine ester has the advantages of increased aqueous solubility,increased absorption from the gastrointestinal (GI) tract resulting inincreased bioavailability, and increased stability, especially forsolution formulations. Increased bioavailability allows smaller doses tobe utilized with greater effect, thereby resulting in fewergastrointestinal side effects. Further, more varied formulationpossibilities are feasible, for example, the product may be formulatedin tablet or capsule form with dextrose and/or phosphate for ease of useand effectiveness.

Once the product is ingested 108, the body metabolizes and activates theproduct by esterases 110, which may be found in the intestinal lumen,epithelial cells and the blood. The esterases convert the product tocreatine 114 and an alcohol 116. Thus, the current invention supplementsthe amount of creatine normally available to the muscle therebyincreasing phosphocreatine levels and decreasing the recovery timerequired before the muscle can perform activity. Further, the resultantalcohols, such as ethanol, glycerol, benzyl alcohol, tert-butyl alcohol,are relatively harmless. See Budavari, S. (Ed.) The Merck Index. Merckand Co., Inc., Whitehouse Station, N.J., 1996, which is hereinincorporated by reference in its entirety. For example, benzyl alcoholis used as a pharmaceutical preservative.

Solubility and permeability are two important factors in the amount of acompound made available to an organism, otherwise known asbioavailability. Solubility refers to the amount of the compound thatmay be dissolved, wherein permeability refers to the ability of thecompound to penetrate across a barrier, such as a membrane, cell walland the like. In terms of solubility, creatine ethyl ester is a greatdeal more soluble that creatine. Utilizing a physiological buffersolution (PBS), laboratory analysis indicates that creatine monohydratehas a solubility limit of approximately 10 mg/ml. This value may beoverly generous, as a great deal of vortexing of the sample and briefheating of the sample to 37 degrees Celsius had to be performed to evenachieve that result. However, the creatine ethyl ester is readilysoluble in room temperature PBS with solubility over 200 mg/ml.

With regard to permeability, a laboratory analysis was performedcomparing the creatine monohydrate to creatine ethyl ester in MDCKmonolayers. The MDCK are a canine kidney epithelial cell line that hasbeen used as an in vitro model for assessing drug permeability. In theMDCK monolayers, creatine monohydrate showed approximately 10% flux overone hour. In other words, 10% of the original amount of creatinemonohydrate added to one side of the MDCK monolayer made it across tothe other side in a 60-minute period. For creatine ethyl ester, thepermeability is quite higher, averaging approximately 20% flux over onehour. Similar results are expected in a Caco-2 monolayer, which may beused as an in vitro model for intestinal absorption. Thus, the creatineester of the present invention has the unexpected result of bothincreased solubility and membrane permeability, and thus greaterbioavailability, as shown through the following table and graph depictedin FIG. 1D. Substance Conc. at Saturation mg/ml Partition CoefficientCreatine  15.6 +/− 2.1 0.015 +/− 0.007 Creatine Ethyl Ester 205.9 +/−1.5 0.074 +/− 0.008 Creatine Benzyl Ester 89.26 +/− 0.8 0.106 +/− 0.01 

Although a creatine ethyl ester compound has been described, it shouldbe apparent that a wide variety of creatine ester compounds and saltsthereof are contemplated by the present invention without departing fromthe spirit and scope thereof, examples of which are shown in FIGS. 2A,2B, 2C, 2D, 2E, 2F, 2G, 2H, 2I, 2J, 2K, 2L, 2M and 2N. For example, amono-creatine glycerol, di-creatine glycerol, tricreatine glycerol andthe like, may be utilized as a pronutrient of the present invention, theformula for a tricreatine glycerol is as follows:

Another example of a creatine ester compound suitable for use as apronutrient includes creatine phosphoester, the formula of which is asfollows:

Thus, the present invention provides multiple ester derivatives ofcreatine for use as pronutrients having increased solubility andpermeability over creatine itself. The advantages of creatinepronutrients of the present invention would be useful in athleticperformance markets, therapeutic markets targeting patients withdiseases involving reduced muscle performance/loss of muscle mass.livestock/animal food products market, and the like.

Referring generally now to FIGS. 3 and 4, an exemplary embodiment of thepresent invention is shown wherein the production of an ester derivativeof creatine is shown. A creatine ester may be formed by reacting ahydrated form of creatine or anhydrous creatine with various alcohols inan acidic atmosphere. Under these conditions, various ester procreatinecompounds may be formed, generally as white precipitates. The resultantcreatine esters may be further purified by solvating in an alcohol atelevated temperatures and then cooling to form the ester procreatinecompound. The final recrystallization step may not be required, as theinitial precipitate is generally pure. However, such an extra step maybe useful to ensure that the purest form of the creatine pronutrient hasbeen obtained.

For example, as shown in FIG. 3, creatine monohydrate may be solvated indry ethyl alcohol in an atmosphere of hydrochloric acid at ambienttemperatures. The resultant creatine ethyl ester compound is solid atambient temperatures. While not functionally necessary, the resultantcreatine ethyl ester may be further purified with the use of ethylalcohol at an elevated temperature to solvate the creatine ethyl esteraway from possible contaminates contained in the solid reactionmaterial. Purified creatine ethyl ester may then be achieved uponcooling the solvated creatine ethyl ester. It should also be apparentthat anhydrous creatine may also be utilized without departing from thespirit and scope of the present invention.

Although the formulation of creatine ethyl ester is disclosed, it shouldbe apparent that a variety of creatine esters may be produced utilizinganalogous reaction systems without departing from the spirit and scopeof the present invention. See Dox., A. W.; Yoder, L. Esterification ofCreatine. J. Biol. Chem. 1922, 67, 671-673, which is herein incorporatedby reference in its entirety. For instance. a variety of methods ofproducing a creatine ester are contemplated without departing from thespirit and scope of the present invention, such as the methods andprocess shown in FIG. 4, wherein X may include a leaving group. Althoughthe use of creatine monohydrate is disclosed, a variety of creatinecontaining starting compounds are contemplated by the present invention,creatine monohydrate being disclosed merely because of its availability.

Referring now to FIG. 5, an embodiment of the present invention is shownwherein anhydrous creatine is solvated in dry benzyl alcohol in anatmosphere of hydrochloric acid at ambient temperatures to produce acreatine ester. The resultant creatine benzyl ester compound is a whitesolid at ambient temperatures. While not functionally necessary, theresultant creatine benzyl ester may be further purified with the use ofethyl alcohol at an elevated temperature to solvate the creatine benzylester away from possible contaminates. Purified creatine benzyl estermay then be achieved upon cooling the solvated creatine benzyl ester. Asstated earlier, the final recrystallization step may not be required asthe initial precipitate is relatively pure. However, such an extrapurification step may be useful to ensure that the most pure form of thecompound has been obtained.

As discussed earlier, creatine esters may also be synthesized fromanhydrous creatine using esterification methods and isolated as theirhydrochloride salts. For example, creatine ethyl ester hydrochloride maybe synthesized by treatment of anhydrous creatine with ethanolic HCl atroom temperature. See Dox., A. W.; Yoder, L. Esterification of Creatine.J. Biol. Chem., 67, 671-673, (1922) which is herein incorporated byreference in its entirety.

-   -   creatine ethyl ester hydrochloride        Using this method, creatine ethyl ester hydrochloride was        synthesized in 74% yield after a single recrystallization from        ethanol.

Creatine esters creatine benzyl ester hydrochloride and creatinemonoglycerate ester hydrochloride may similarly be obtained by exposureof anhydrous creatine with excess HCl-saturated benzyl alcohol andglycerol, respectively. It should be apparent that stereoisomers, suchas a stereoisomers of creatine monoglycerate ester hydrochloride, andthe compounds shown in FIGS. 2B, 2E, 2F, 2G, 2J and the like, are alsocontemplated by the present invention.

Creatine tert-butyl ester hydrochloride may be obtained by treatment ofcreatine acid chloride with tert-butanol and zinc chloride. See Rak, J.;Lubkowski, J.; Nikel, I.; Przubulski, J.; Blazejowski, J. ThermalProperties, Crystal Lattice Energy, Mechanism and Energetics of theThermal Decomposition of Hydrochlorides of 2-Amino Acid Esters,Thermochimica Acta 171, 253-277 (1990); Yadav, J. S.; Reddy, G. S.;Srinivas, D.; Himabindu, K. Zinc Promoted Mild and Efficient Method forthe Esterification of Acid Chlorides with Alcohols, Synthetic Comm. 28,2337-2342 (1998). Creatine tert-butyl ester hydrochloride may also beobtained by treatment of anhydrous creatine with tert-butanol andanhydrous magnesium sulfate and catalytic sulfuric acid. See Wright, S.W.; Hageman, D. L.; Wright, A. S.; McClure, L. D. ConvenientPreparations of t-Butyl Esters and Ethers from t-Butanol, TetrahedronLett. 38, 7345-7348 (1997), which are herein incorporated by referencein their entireties.

Bis creatine glycerate ester dihydrochloride ester, may be obtained bytreatment of creatine acid chloride with a half-molar equivalent ofanhydrous glycerol. See Rak, J.; Lubkowski, J.; Nikel, I.; Przubulski,J.; Blazejowski, J. Thermal Properties, Crystal Lattice Energy,Mechanism and Energetics of the Thermal Decomposition of Hydrochloridesof 2-Amino Acid Ester, Thermochimica Acta 71, 253-277 (1990), which isherein incorporated by reference in its entirety.

Alternatives to these methods include transesterification reaction ofCE1 using either catalytic diphenyl ammonium triflate and trimethylsilylchloride (Wakasugi et al., 2000) or catalytic potassium tert-butoxideand 1 equivalent of tert-butyl acetate. Creatine acid chloride may alsobe used rather than anhydrous creatine in the esterification reactions.See Wakasugi, K.; Misake, T.; Yamada, K.; Tanabe, Y. Diphenylammoniumtriflate (DPAT): Efficient Catalyst for Esterification of CarboxylicAcids and For Transesterification of Carboxylic Esters With NearlyEquimolar Amounts of Alcohols, Tetrahedron Lett. 41, 5249-5252 (2000),which is herein incorporated by reference in its entirety.

Regioselectivity problems in the formation of creatine esters, such ascreatine monoglycerate ester hydrochloride, Bis creatine glycerate esterdihydrochloride ester, and the like, may be addressed by selectiveesterification of the primary alcohol functional group(s) of glycerolwith creatine acid chloride in the presence of N,N-diisopropylethylamineor 2,4,6-collidine at low temperatures. See Ishihara, K.; Kurihara, H.;Yamamoto, H. An Extremely Simple, Convenient. and Selective Method forAcetylating Primary Alcohols in the Presence of Secondary Alcohols, J.Org Chem. 58, 3791-3793 (1993), which is herein incorporated byreference in its entirety.

Creatine esters may be purified by crystallization, flash columnchromatography, and the like, if desired, and the structures and purityconfirmed by analytical HPLC, ¹H and ¹³C NMR, IR, melting point andelemental analysis. The following data was obtained through nuclearmagnetic resonance spectroscopy of the corresponding compounds:

Creatine ethyl ester hydrochloride

¹H NMR (500 MHz, CDCl₃) δ 1.12 (dq, J=6.0 Hz, J=1.0 Hz, 3H), 2.91, (s,3H), 4.10-4.11 (m, 4H).

Creatine benzyl ester hydrochloride

¹H NMR (500 MHz, DMSO-d₆) δ 3.03 (s, 3H), 4.13 (s, 2H), 5.06 (s, 2H),7.22-7.38 (m, 5H).

It is understood that the specific order or hierarchy of steps in themethods disclosed are examples of exemplary approaches. Based upondesign preferences, it is understood that the specific order orhierarchy of steps in the method can be rearranged while remainingwithin the scope of the present invention. The accompanying methodclaims present elements of the various steps in a sample order, and arenot meant to be limited to the specific order or hierarchy presented.

It is believed that the creatine ester pronutrient compounds andformulations of the present invention and many of its attendantadvantages will be understood by the forgoing description. It is alsobelieved that it will be apparent that various changes may be made inthe form, construction and arrangement of the components thereof withoutdeparting from the scope and spirit of the invention or withoutsacrificing all of its material advantages. The form herein beforedescribed being merely an explanatory embodiment thereof. It is theintention of the following claims to encompass and include such changes.

1. A method for providing creatine to an animal, comprising orallyreceiving creatine ethyl ester and/or a salt of creatine ethyl ester bythe animal in a form suitable for being modified by the animal intocreatine.
 2. The method according to claim 1, wherein said animal is ahuman.
 3. The method according to claim 1, wherein said animal islivestock.
 4. The method according to claim 1, wherein the creatineethyl ester and/or salt of creatine ethyl ester is in solid form.
 5. Themethod according to claim 4, wherein the solid form further comprises atleast one of dextrose and phosphate.
 6. The method according to claim 4,wherein the solid form is configured as at least one of a tablet and acapsule.
 7. The method according to claim 1, wherein the creatine ethylester and/or salt of creatine ethyl ester is in a form suitable forliquid delivery.
 8. The method according to claim 7, wherein thecreatine ethyl ester and/or salt of creatine ethyl ester is in the formof an aqueous solution or emulsion.
 9. The method according to claim 1,comprising orally receiving creatine ethyl ester by a human.
 10. Themethod according to claim 1, comprising orally receiving a creatineethyl ester salt by a human.
 11. The method according to claim 10,comprising orally receiving creatine ethyl ester hydrochloride by ahuman.
 12. A food supplement, wherein said food supplement is suitablefor administration to an animal and comprises creatine ethyl esterand/or a salt of creatine ethyl ester.
 13. The food supplement asclaimed in claim 12, wherein said animal is a human.
 14. The foodsupplement as claimed in claim 12, wherein said supplement is in theform of a tablet or capsule.
 15. The food supplement of claim 12,wherein said food supplement further comprises at least one of dextroseand phosphate.
 16. The food supplement of claim 13, comprising creatineethyl ester.
 17. The food supplement of claim 13, comprising creatineethyl ester salt.
 18. The food supplement of claim 13, comprisingcreatine ethyl ester hydrochloride.
 19. The food supplement of claim 13,wherein said food supplement consists essentially of creatine ethylester and/or a salt of creatine ethyl ester.
 20. The food supplement ofclaim 19, wherein said food supplement further includes at least one ofdextrose and phosphate.
 21. The food supplement of claim 19, whichconsists essentially of creatine ethyl ester.
 22. The food supplement ofclaim 19, which consists essentially of creatine ethyl ester salt. 23.The food supplement of claim 19, which consists essentially of creatineethyl ester hydrochloride.
 24. The food supplement of claim 21, whereinsaid food supplement further includes at least one of dextrose andphosphate.
 25. The food supplement of claim 22, wherein said foodsupplement further includes at least one of dextrose and phosphate. 26.The food supplement of claim 23, wherein said food supplement furtherincludes at least one of dextrose and phosphate.
 27. The food supplementof claim 19, wherein said supplement is in the form of a tablet orcapsule.
 28. The food supplement as claimed in claim 20, wherein saidsupplement is in the form of a tablet or capsule.
 29. The foodsupplement as claimed in claim 21, wherein said supplement is in theform of a tablet or capsule.
 30. The food supplement as claimed in claim22, wherein said supplement is in the form of a tablet or capsule. 31.The food supplement as claimed in claim 23, wherein said supplement isin the form of a tablet or capsule.
 32. The food supplement as claimedin claim 24, wherein said supplement is in the form of a tablet orcapsule.
 33. The food supplement as claimed in claim 25, wherein saidsupplement is in the form of a tablet or capsule.
 34. The foodsupplement as claimed in claim 26, wherein said supplement is in theform of a tablet or capsule.